Query on eBPF Map iterator in Kernel space

Query on eBPF Map iterator in Kernel space

[Shwetha Vittal]

Hi,

Is there any way to iterate through eBPF Map elements in kernel space.
I know that there is one at user space bpf_map_get_next_key(). But it
doesn't work when tried in kernel space. I have a requirement to find
the record in the eBPF map which has the least value in kernel space
and pick it for further packet processing and therefore need to
iterate through eBF Map .

Kindly help

Thanks
Shwetha

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Re: Query on eBPF Map iterator in Kernel space

[Toke Høiland-Jørgensen]

Shwetha Vittal <cs19resch01001@iith.ac.in> writes:

> Hi,
>
> Is there any way to iterate through eBPF Map elements in kernel space.
> I know that there is one at user space bpf_map_get_next_key(). But it
> doesn't work when tried in kernel space. I have a requirement to find
> the record in the eBPF map which has the least value in kernel space
> and pick it for further packet processing and therefore need to
> iterate through eBF Map .

There will be soon:
https://lore.kernel.org/bpf/20210226204920.3884074-1-yhs@fb.com/

-Toke

Re: Query on eBPF Map iterator in Kernel space

[Y Song]

On Mon, Mar 1, 2021 at 6:44 AM Toke Høiland-Jørgensen <toke@redhat.com> wrote:
>
> Shwetha Vittal <cs19resch01001@iith.ac.in> writes:
>
> > Hi,
> >
> > Is there any way to iterate through eBPF Map elements in kernel space.
> > I know that there is one at user space bpf_map_get_next_key(). But it
> > doesn't work when tried in kernel space. I have a requirement to find
> > the record in the eBPF map which has the least value in kernel space
> > and pick it for further packet processing and therefore need to
> > iterate through eBF Map .
>
> There will be soon:
> https://lore.kernel.org/bpf/20210226204920.3884074-1-yhs@fb.com/

What kind of maps are you trying to iterate? The above patch set
supports hash and array maps. Also, the above patch set has been
merged into bpf-next repo. Feel free to experiment with it!

>
> -Toke
>

Re: Query on eBPF Map iterator in Kernel space

[Shwetha Vittal]

Sure thanks. I have created a hashmap. I will try with the new
proposed API  long bpf_for_each_map_elem(struct bpf_map *map, void
*callback_fn, void *callback_ctx, u64 flags) from bpf-next repository.

Thanks
Shwetha

On Tue, Mar 2, 2021 at 11:55 AM Y Song <ys114321@gmail.com> wrote:
>
> On Mon, Mar 1, 2021 at 6:44 AM Toke Høiland-Jørgensen <toke@redhat.com> wrote:
> >
> > Shwetha Vittal <cs19resch01001@iith.ac.in> writes:
> >
> > > Hi,
> > >
> > > Is there any way to iterate through eBPF Map elements in kernel space.
> > > I know that there is one at user space bpf_map_get_next_key(). But it
> > > doesn't work when tried in kernel space. I have a requirement to find
> > > the record in the eBPF map which has the least value in kernel space
> > > and pick it for further packet processing and therefore need to
> > > iterate through eBF Map .
> >
> > There will be soon:
> > https://lore.kernel.org/bpf/20210226204920.3884074-1-yhs@fb.com/
>
> What kind of maps are you trying to iterate? The above patch set
> supports hash and array maps. Also, the above patch set has been
> merged into bpf-next repo. Feel free to experiment with it!
>
> >
> > -Toke
> >

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Re: Query on eBPF Map iterator in Kernel space

[Y Song]

On Tue, Mar 2, 2021 at 4:55 PM Shwetha Vittal <cs19resch01001@iith.ac.in> wrote:
>
> Sure thanks. I have created a hashmap. I will try with the new
> proposed API  long bpf_for_each_map_elem(struct bpf_map *map, void
> *callback_fn, void *callback_ctx, u64 flags) from bpf-next repository.

Great. Let us know if you hit any issues or have any suggestions. Thanks!

>
> Thanks
> Shwetha
>
> On Tue, Mar 2, 2021 at 11:55 AM Y Song <ys114321@gmail.com> wrote:
> >
> > On Mon, Mar 1, 2021 at 6:44 AM Toke Høiland-Jørgensen <toke@redhat.com> wrote:
> > >
> > > Shwetha Vittal <cs19resch01001@iith.ac.in> writes:
> > >
> > > > Hi,
> > > >
> > > > Is there any way to iterate through eBPF Map elements in kernel space.
> > > > I know that there is one at user space bpf_map_get_next_key(). But it
> > > > doesn't work when tried in kernel space. I have a requirement to find
> > > > the record in the eBPF map which has the least value in kernel space
> > > > and pick it for further packet processing and therefore need to
> > > > iterate through eBF Map .
> > >
> > > There will be soon:
> > > https://lore.kernel.org/bpf/20210226204920.3884074-1-yhs@fb.com/
> >
> > What kind of maps are you trying to iterate? The above patch set
> > supports hash and array maps. Also, the above patch set has been
> > merged into bpf-next repo. Feel free to experiment with it!
> >
> > >
> > > -Toke
> > >
>
> --
>
>
> Disclaimer:- This footer text is to convey that this email is sent by one
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